Drill and throwaway insert

Abstract

A drill improving the aligning accuracy of an insert and achieves a stable machining operation while maintaining the strength of the drill main body. The drill includes a drill main body rotatable about an axis, and a throwaway insert detachably attached to the drill main body. The drill main body includes a concave groove opening at a distal end face thereof, the concave groove includes guiding grooves extending in the direction of the axis on an inner surface thereof, the throwaway insert includes convex portions on an outer surface that are engageable with the guiding grooves, and the concave groove is formed so as to accommodate the throwaway insert. The throwaway insert is attached to the drill main body by insertion into the concave groove in a direction from the distal end face to the concave groove while engaging the convex portions with the guiding grooves.

1. A drill having an axis comprising:
 a drill main body being rotatable about the axis including:
 a distal end face formed in an isosceles triangle shape; 
 a concave groove which opens to the distal end face and forms a plate-shape space along the axis; and 
 a plurality of guiding grooves provided on an inner surface of the concave groove, and extending in a direction of the axis; and 
 
 a throwaway insert formed in a plate-shape and detachably attached to the plate-shape space of the drill main body including:
 a plurality of convex portions provided on an outer surface of the throwaway insert, which are formed such that each of ridges thereof extends in the direction of the axis, arranged side by side in a direction crossing the axis, and engageable with the guiding grooves; and 
 tapered portions, each of which is connected to each proximal end of the convex portions, and inclined so that a height thereof with respect to an outer surface of the throwaway insert is lowered toward a proximal end of the throwaway insert along the direction of the axis, 
 
 wherein distal ends of the guiding grooves and the tapered portions are arranged following the isosceles triangle shape of the distal end face of the drill main body, and 
 the throwaway insert is attached to the drill main body by being inserted into the concave groove along the axis from the distal end face to the concave groove while engaging the convex portions with the guiding grooves. 
 
   
   
     2. A drill according to  claim 1 , wherein
 the drill main body is provided with a flow path which extends from a bottom face of the concave groove that faces toward the distal end face, and which opens outside the drill main body so as to allow a predetermined fluid to flow therethrough, and 
 gaps are formed between the guiding grooves and the convex portions engaging with each other, which allow the fluid to flow between a distal end of the throwaway insert and the proximal end thereof that faces the bottom face of the concave groove. 
 
   
   
     3. A drill according to  claim 2 , wherein the bottom face is provided with a cavity which is connected to the gaps. 
   
   
     4. A drill according to  claim 2 , wherein at least ridge portions of the convex portions ridge portions or between the guiding grooves are chamfered so as to have flat surfaces. 
   
   
     5. A drill according to  claim 1 ,
 wherein lengths of the tapered portions are set so as to be gradually decreased, in a direction crossing a direction of insertion, from a center toward an end of the outer surface.